Underground or buried vaults, pits chambers or boxes used in the utilities, security, and rail line sectors or other industries can contain co-axial or optical fiber, copper cable as well as gas and power lines and other conduits, industrial valves, WI-FI antennas, etc. Vaults and pits for underground utilities often need to be opened for making repairs or for enhancing services. Typically, utility vaults and pits include a concrete, polymer concrete, or plastic lid which is opened by a tool or pick with a hook at one end. The hook is inserted through a hole in the lid or cover and is used for prying the lid or cover away from it's opening atop the vault or pit.
In the course of using the underground box the cover or lid may be installed at approximately grade level. These covers or lids of various materials such as plastic, concrete, polymer concrete and fiber reinforced composites are secured in place by various means such as straight bolts or L-bolts etc. The bolt typically passes through the cover and into the underground box where it is screwed into a retained nut or similar device thus fastening the cover to the box. This fastening system is highly prone to failure and a great many of the installed box/cover units are deliberately damaged to regain entry into the box chamber and access internal infrastructure such as copper or fiber-optic enclosures. The damage is typically, but not limited to, breaking the corners of the cover where the bolts which are typically positioned onto opposing corners attach the cover to the box. This of course means that the cover is no longer secured to the box and the cover is significantly weakened to the point that it would not likely pass load requirements regulated for that installation proximity to the vehicular loading. As the cover is no longer secured by the bolts, which typically include tamper-resistant features such as “Penta” head designs which require specialized tools for access not commonly available, the utility vault is subject to vandalism, theft or unwanted damage due to the fact that ready access to the infrastructure which was intended to be protected by such security features is readily available.
Failure of the fastening systems typically occurs by two mechanisms wherein either the bolt and nut becomes seized together and the bolt cannot be turned for removal, or the bolt and nut become seized and the nut breaks free of its retainer and spins with the bolt as it is turned. In some systems there is an additional failure mode where the bolt threads are stripped and the bolt cannot be removed. All of these situations prevent removal of the cover and lead technicians to break the cover to gain access. Further exacerbation of this problem is the recent development and deployment of advanced composite materials, used to manufacture the covers, which cannot be broken at the corners as older materials could and require extreme measures to re-enter the box if the retaining systems fail. These scenarios are common place and prevalent across all infrastructure companies deploying underground boxes including but not limited to, telecommunications, transportation, energy distribution and other utilities.
Various attempts to solve the fastening system failure have been tried. For example, to address some aspects of bolt/nut seizure such as when stainless steel nuts and bolts gall causing them to seize, either the nut or bolt has been substituted with a brass nut or bolt or an anti-seize compound is added to prevent stainless on stainless galling. However, while galling can be an issue, a much larger problem is thread contamination with particulates especially sand, soil, cement and granules of polymer concrete. As these installations are in soil or sidewalks, particulates are almost always contaminating the threads and the addition of anti-seize compounds give the particulates a grease-like compound to adhere to and carry them into the bolt/nut thread interface. Thus, most of the failures are due to contamination of the threads and the current solutions do not address this problem.
Therefore a need exists for an improved fastening system for attaching a lid or cover to an underground or buried vault, pit, chamber or box which addresses the drawbacks of previous fastening systems and which allow for gaining entry into the chamber of the box without damaging the lid or cover.